Can Someone Help Me Understand This User Defined Function

I have a user defined function that is being called
PadStringWithNullAndTrim(column_name,SPACE(1),38,' R')

I didn't understand why the space(1) and why have they used 38 and ultimately char 'R'
I am assuming 'R' to act as null character.
I don't have the code for the user defined function
Can someone please help me in figuring it out?

Is it possible that they are trying to pad 38 out of 40 characters with spaces, and then put a space plus the letter R at the end? In other words, they really just want to put an R at the end of the string? Maybe this helps in some other sorting of data. Hard to say without the code I suppose?

Thanks,
Colby

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Is it possible that they are trying to pad 38 out of 40 characters with spaces, and then put a space plus the letter R at the end? In other words, they really just want to put an R at the end of the string? Maybe this helps in some other sorting of data. Hard to say without the code I suppose?

Actually I was given a stored procedure and I am supposed to try and get
the same output from that stored procedure after I modify it according to
the tables, functions, etc. that I have with me. So that's the reason I was
trying to get an idea about what that function signature was meant for.

I know it sounds stupid, but the thing is that I don't have the actual
function I mentioned. I got the stored procedure from a client, now I need
to know what they have been trying to do so that I can make the changes and
get stored procedure to run for me. They didn't give me the code for the
user defined function.

Before you start coding, you may want to consider an alternate interpretation.

You have a function with four arguments: the input string, the character to use to extend the string (a space), the desired length (38), and the "justification" (whether the padding is on the Left or the Right).

Your profile says you are a student. If we're being asked for help with an assignment, it would be nice to know. As a teacher and an analyst, I agree with mcdonelly, Modify the parameters one at a time to confirm or refine guesses as to their effect. Move on to pairwise and greater changes to further confirm your hypotheses. If you stay in IT, this won't be the last "black box" you encounter.

Oh, yes, definitely another guess. However, let's call it an "educated guess", based on four decades of experience with formatting and text processing.

I can't think of many reasons to construct a function that has a separate parameter just to add a weird character at the end of a string; I can think of lots of reasons to create a procedure that can "justify" a string to either the left or the right.

I've worked with a variety of languages and systems that did provide methods to pad strings. In almost every case, one of the parameters was the character to use for padding (the typical cases being: a space when left justifying an alphanumeric string (by adding spaces on the right); or a zero when right justifying a numeric string (by adding zeros on the left).

I know that you're an experienced programmer, and I'm sure that there are domains where you can look at a function signature and, by associating it with similar functions that you have encountered in the past, make similar "educated guesses" about the intent and operation.